Telephone-transmitter.



PATENTED DEC. 20, 1904.

E. E. RIBS. TELEPHONE TRANSMITTER.

APPLIOATION FILED JUNE 23. 1900.

2 SHBBTS-SHEET 1.

N0 MODEL.

W v n ma w w n M m 9 0 Witmsszsa v Lam No. 777,808. PATENTED DEC. 20, 1904.

' E. E. RIBS.

TELEPHONE TRANSMITTER.

APPLICATION FILED JUNE 23, 1900. N0 MODEL. 2 sums-sum 2.

.m P Mill/l Witness; Am/enter w w 31w. 5 TM attornw UNITED STATES Patented December 20, 1904:.

ELIAS E. RIES, OF NElV YORK, T. Y.

TELEPHONE-TRANSMITTER.

STEECIFIGATION formingpart of Letters Patent N 0. 777,808, dated December 20, 1904. Application filed June 23, 1900. Serial No. 21,322.

To (tZZ whom, it may concern:

Be it known that I, ELIAS E. Thus, a citizen of the United States, and a resident of New York city, in the county of New York and State of New York, (post-oflice address, 346 Broadway,) have invented certain new and useful Improvements in Telephone-Transmitters, of which the following is a specification.

The present invention relates to a new method of transmission of speech electrically; and itconsists, substantially, in the utilization of the principle of capillary attraction for controlling the resistance of an electric circuit instead of using variable pressure, as is the ordinary practice. It is well known that when two surfaces of glass or other material having an aflinity for a given liquid or fluid in which both are partially immersed are brought closely together withoutactually touchingeach other the fluid will rise between them of its own accord to a height considerably above that of its normal level or of its general surrounding level and in doing so will spread over a considerable area of the surface between which it rises. On the other hand, when the surfaces are separated the column of liquid between them, being no longer capable of selfsupport, will descend until it has reached the general level, when the plates or surfaces have been sufficiently separated, and in doing so greatly reducing the surface area over which it spreads. This is especially the case when the lower edges of the surfaces are nearly in contact and the motion of one or both plates is such as to cause their upper edges to approach and diverge respectively. hen the surfaces instead of being vertical, or approximately so, are both horizontal and close together and a drop or small quantity of the fluid is placed at the center of the lower surface, which may be in the form of a plate or disk, it will assume the shape of a flattened bead or film spreading over both surfaces through its chemical affinity or capillary action, and if the upper surface or disk be slightly lifted the bead will tend to rise with itand in doing so become elongated and at the same time contracted in width to a considerable extent, so that the portions of the surfaces bridged bythe fluid, as well as the crosssection of the bead itself, is relatively small. This action, as already stated, takes place without pressure upon the fluid. In my present invention I take advantage of this property of certain fluids by utilizing it for the purpose of causing variations in the electrical resistance of the transmitter-circuit in accordance with the vibrations of the transmitter-diaphragm in such a manner that the diaphragm is kept perfectly free to vibrate under the influence of the sound-wave without being dampened or interfered with by the mechanical resistance or inertia of the usual carbon or other microphone contacts which oppose its free motion and demand the exertion of a greater or less pressure of the diaphragm upon them. I am, furthermore, enabled to so utilize this property of capillary attraction, and also in some cases that of surface tension, as to produce a wider range or variation in current strength in the primary circuit, and hence in the secondary or line, than is possible with the usual forms of microphones depending upon variable pressure alone or upon such pressure coupled with a slight flattening of a comparatively rigid surface or unyielding electrode.

There are numerous types of apparatus that I may construct to carryout my invention. In practice, however, I prefer to make my transmitter of a solid. horizontally-disposed lower disk or base-piece forming one electrode and having aslight central cavity of such shape as to tend to confine to such center a small quantity of conducting or semiconducting fluid. Above this disk and substantially parallel with it and having its periphery seated upon an insulating-cushion forming a closed chamber of the two disks is the vibrating diaphragm, over which is a curved mouthpiece leading to the outside of the transmitter-box. The diaphragm forms the other electrode, and it, together with the inner surface of the lower or back plate, is preferably plated with gold, aluminium, or other non-oxidizable metal having the necessary aflinity or attraction for the fluid employed, which may be of any desired nature capable of readily spreading itself over the two surfaces in the manner described and is sufficiently mobile, such as an ordinary battery solution of the requisite degree of conductivity. I have obtained excellent results with a number of different fluids, including mercury. I have also used a non-conducting are preferably employed for supplying any loss and for varying the level of the liquid already in the transmitter-chamber, which latter is so shaped that the fluid will naturally assume its proper position when the instrument is set up for service. Instead of the diaphragm itself serving as one electrode it will be obvious that it may be connected at its center, by means of a short rod, either to an amplifying-plate or diaphragm-electrode or to a special conical-shaped electrode designed to be vibrated by it in proximity to a similarlyshaped conical or concave lower electrode containing the fluid, the sides of the lower electrode being slightly more acute or inclined than those of the upper one, so that when the latter approaches the former the capillary space nearer the periphery of the two electrodes will be thinner and more effectivethat is to say, conducive to a larger and more pronounced increase in the fluid-covered area of the two surfaces, and vice versa, thereby causing a greater variation in the electrical resistance of the bridging fluid upon which the action of the transmitter depends.

In the accompanying drawingsI have illustrated various forms of apparatus adapted for carrying out my invention.

Figure 1 shows in vertical section a form of instrument in which the two plates which include the capillary fluid between them are arranged in vertical position. Fig. 2 shows a modification in which the sound-waves communicate motion to the liquid instead of to the electrode. Figs. 3 and I show forms wherein the electrodes or plates are arranged hori- Zontally.

Referring to Fig. 1, 2 is a diaphragm designed to receive the sound-waves directed upon it by the mouthpiece 3 of the instrument. The diaphragm and mouthpiece may be mounted together after the manner usual with telephone-transmitters and as clearly shown. 4: is the support or easing of the instrument and is made to form a chamber containing the liquid and the electrodes. 5 is one electrode,

h un g by a suitable pivotal or pend ulous suspension and mechanically connected with the diaphragm by a pin or other connection, so as to partake of the motion of the diaphragm When subjected to the influence of sound-waves. In Fig. 1 it is shown as provided with a pendulous suspension consisting of ahook at one end of the plate or one electrode and acavity in the front of the case, into which the hook enters. The electrode may be included in the electric circuit by the electric connection formed between the hook and easing when the latter is of metal or through the diaphragm or in any other desired Way. Obviously, also, the electrode might be mounted and connected with the diaphragm in other ways, so as to partake of the motions thereof. '6 is another plate or rod electrode suspended or supported in close proximity to 5, so as to form a very narrow space between them, in which the liquid in the casing rises by capillary attraction. Electrode 6 may be supported in the manner indicated from the easing 4 by an insulated support, so that the electrodes 5 6 may form terminals of anelectric circuit leading from a suitable generator, as well understood in the art and as fully shown in Fig. 2.

The support for electrode 6 is preferably of such character as to permit it to be adjusted toward and away from the opposite electrode by means of an adjusting-screw 10, which latter should be in this particular form of instrument also insulated from the casing. By means of this adjustment the initial or normal extent of wetted surface covered by the capillary film upon the opposing faces of the electrodes may be adjusted. The electrodes are so arranged, by preference, that the space between them narrows gradually in an upward direction, so that the amplitude of the variations in the electrical resistance will be increased in a more pronounced degree with j an increase in vibration of the electrode 5 through the operation of the diaphragm 2. When the electrode 5 approaches the electrode 6 under the action of the sound-waves, the liquid rises still farther in the space between them through capillary attraction, thus increasing the wetted surface upon the electrodes, and thereby diminishing the electric resistance interposed in the circuit of the generator by the liquid. When the diaphragm recedes, thus increasing the space between the electrodes, the liquid falls away and the resistance increases.

An adjusting device, such as indicated at 11, may be employed to vary the cubical contents of the liquid-containing chamber and to thereby adjust the initial extent of wetted surface.

In the modification of my invention shown in Fig. 2 one electrode, 5', is formed by the back plate of the metallic casing for the instrument, and the other, 6, is suitably mounted, as before described, and is preferably cathis condition, an elastic seal or washer 22 pable of adjustment toward and away from 5. The electrodes are so arranged that the space between them narrows upwardly, so that if by any external means the height of the liquid film is raised the capillary attraction will produce a further spreading of the film, owing to the greater proximity of the surfaces, and thereby vary the resistance. In this form of instrument the sound-waves operate hydrostatically to raise the level of the liquid in the space between the electrodes so that capillary action will come into place to vary the electric resistance, as before explained. For this purpose the diaphragm may operate directly or indirectly in a manner to reduce the cubic capacity of the liquid-holding space, and thereby raise its level; but preferably it is made to act, as shown, upon a body of air or gas interposed between it and the liquid, so as to permit freer movement of the diaphragm than would be the case if the diaphragm formed a wall of the liquid-containing space.

The diaphragm 2 is made, preferably, of rubber or suitable elastic material and is disposed horizontally over the liquid in a chamber which communicates with that in which the electrodes are disposed, so that when the liquid is forced out of the first chamber by the action of a sound-wave operating on the diaphragm it will be caused to assume a higher level in the other chamber.

Preferably the cross-sectional area of the vertical chamber or space containing the electrodes is made small as compared with that of the diaphragm, so that the movement of the diaphragm will result in an amplified movement of the liquid column in which the electrodes are contained, according to well-known principles of hydrostatics. To better realize placed in the smaller vertical chamber, as indicated, so that the liquid shall be free to rise only in the space between the electrode 6 and electrode 5. The elastic seal or cushion 22, while closing the space, as shown, permits an adjustment of the electrode 6 by means of the screw 10. An air-vent may be provided, as indicated at 23.

While I show a flexible diaphragm for receiving the sound-waves, it is obvious that the diaphragm might be dispensed with and the soundwaves permitted to fall directly upon the surface of the liquid. So, also, in other forms of the instrument one of the plate-electrodes might be arranged to receive the sound-waves directly.

Fig. 3 illustrates a modification in which, the electrodes are disposed horizontally. The casing of the instrument in this instance is of non-conducting material, and the electrode 6" rests upon an insulating screw-ring, by which it is clamped against an insulatingwasher may be which holds the diaphragm 2 in place. The diaphragm constitutes the other electrode. 1

Connection with the diaphragm-elcctrode 2 is made by the screw 15 and with electrode 6" by a screw 16. The distance between the electrodes as shown is'exaggerated, and in practice the electrodes would be very much closer together and in any case sufficiently close to cause the liquid to spread out between the electrodes by capillary attraction when one electrode is caused to approach the other by the action of sound-waves operating directly or indirectly upon one or both of the electrodes.

In the modification in Fig. 4, the electrode 5 is attached to the diaphragm2 and the upper electrode is shown as conformed to the dished or concave outline of the lower electrode. In practice the surface of the upper electrode preferably departs in outline from that of the lower in such manner that the space between them shall gradually decrease toward the periphery, thereby producing a large increase in the wetted surface or fluidcovered area for a comparatively smaller movement of the electrodes toward one another, and thereby causing a great amplitude of variation in the resistance in the circuit when the excursions of the diaphragm 2 are large.

It is obvious that my invention may be carried out in very many forms of apparatus and that it is not limited to the special form shown.

By graduating the space between the electrodes as explained, so thatit diminishes from one side or edge of the electrodes toward the other, I introduce an automatic compensation for the dampening action or greater mechan ical resistance to vibrate recurring with the larger excursions or vibrations of the diaphragm when the same is operated by louder sounds, and hence am enabled to transmit sounds with great fidelity. In ordinary telephones the dampening of the diaphragm arising from its now naturally-increasing resistance to vibration as the amplitude of its movement increases prevents it from responding faithfully to the sound-vibrations in respect to amplitude; but with the automatic compensation referred to the diaphragm as it approaches the end of its excursion works upon a capillary film or interval that is narrower or thinner and will hence produce a greater change of resistance for a given movement of the diaphragm, thereby producing changes of resistance thatare a more faithful reflex of the actuating sound-wave. In other words, the changes of resistances produced by the diaphragm as it nears the end of its excursion, where it is dampened, are made proportionately greater for-a given movement, and by proper graduation of the capillary space the variation of resistance, while disproportionate to the movement of the diaphragm, may be made exactly proportionate to the actuating sound-wave.

The special mechancial constructions of apparatus herein shown and described for practicing the methods claimed herein are the subject of claims in my application for patent filed January 11, 1904, Serial No. 188,638, asa division of the present application.

'What I claim as my invention is l. The herein-described improved method of producing variations of resistance in an electric circuitcorresponding in form tosoundwaves, consisting in varying the extent of a wetted surface included in an electric circuit with the wetting liquid by the principle of capillary action, as and for the purpose described.

2. The herein-described method of transmitting speech and other sounds electrically, consisting; in causing an electrical current or currents to pass through a capillary film of conducting or semiconducting fluid, and in varying the area of said capillary film, by and in accordance with the vibrations accompanying said speech or other sounds.

3. The herein-described method of transmitting speech and other sounds electrically, which consists in causing the atmospheric vibrations accompanying said speech or other sounds to vary the electrical resistance of a circuit through a suitable film of conducting or semiconducting liquid adapted to vary its area or cross-section under the influcnceof sating for the dampening eflect of atelephonediaphragm consisting in producing a change "of resistance under the action of the diaphragm whose rate of change increases with the increase in the amplitude of vibration.

6. The herein-described method of neutralizing the dampening effect, of atelephone-diaphragm consisting in automatically raising the rate of change of resistance produced by a vibration thereof as it makes its excursion and approaches the end of a vibration.

Signed at New York, in the county of New York and State of New York, this 13th day of June, A. D. 1900.

ELIAS E. RIES.

Witnesses: 1 DELBERT H. DECKER, ETi-IEL L. LAWLER. 

